1 History of the Army Section, Imperial General Headquarters, 1941-45, p. 9. This volume is No. 72 in the series, Japanese Studies in World War II, of which 113 are now available in OCMH in both the original and translated versions. Although both versions have been used in the preparation of this volume, reference throughout is to the translated version unless otherwise noted. For a description of this series see below, The Sources, pp. 595-96.

3 The plan of operations worked out by Imperial GHQ about the middle of November 1941 was destroyed by fire. Certificate of Yozo Miyama, Chief, Archives Sec, 1st Demobilization Bureau, Defense Doc 2726, International Military Tribunal for the Far East (IMTFE).
The description of Japanese strategic concepts is derived from the following documents: (1) Central Agreement Between the Japanese Navy and Army, (2) The Imperial Navy's Course of Action in Operations Against U.S., Great Britain, and the Netherlands, (3) Combined Fleet Top Secret Operation Order 1, 5 November 1941, and (4) Comments of Former Japanese Officers regarding The Fall of the Philippines. The first two are reproduced in United States Strategic Bombing Survey (USSBS), The Campaigns of the Pacific War (Washington, 1946), Apps. 13 and 14, pp. 43-49; copies of the last two are in OCMH. The orders and plans of the Army General Staff can be found in Hist Army Sec, Imperial GHQ; History of Southern Army 1941-1945, Japanese Studies in World War II, No. 21; 14th Army Opns, 2 vols., Japanese Studies in World War II, Nos. 1 and 2.

4 Hist Army Sec, Imperial GHQ, pp. 10, 15; 14th Army Opns, I, 15.

5 Data on the strength of the Japanese Army and Navy are derived from Hist Army Sec, Imperial GHQ, p. 30. A mixed brigade at this time consisted of three to six infantry battalions in addition to supporting and service troops. Strength varied from 3,000 to 10,000 men. An air regiment was generally composed of three squadrons and was the basic operational unit in the Japanese Army Air Force.

6Southern Army Opns, p. 6. The operations order given by the commander of the Southern Army was destroyed by fire. Certificate of Yozo Miyama, 1st Demob Bureau, Defense Doc 2726, IMTFE.

7Southern Army Opns, pp. 4-6. An air group was roughly the equivalent of a U.S. numbered air force, and was the largest tactical unit in the Japanese Army Air Force at that time.

8Ibid., pp. 6-8; 14th Army Opns, I, 14. Unless otherwise specified, this account of the 14th Army's plan for the conquest of the Philippines is taken from the 14th Army Opns, I and II. The translation has been checked against the original Japanese study prepared by the 1st Demob Bureau.

13 The material on naval plans is taken from Naval Operations in the Invasion of the Philippines, Japanese Studies in World War II, No. 13, 2d Demob Bureau, pp. 1-6. Like other studies in this series, it is filed in OCMH and has been checked against the original. Morison, Rising Sun in the Pacific, pp. 161-63, is useful for the organization of Japan's naval forces. See also Combined Fleet Top Secret Operations Order 1, in Pearl Harbor Attack Hearings, Part 13, Exhibit 8, pp. 432-84.

14 The 11th Air Fleet had originally planned to use carrier-based fighters to neutralize southern Luzon, but the pilots trained for this mission were transferred with their planes to the Pearl Harbor operation. During the fall of 1941 the improvement of the Zero fighters and the rapid advancement in pilot training made it possible to utilize land-based fighters on Formosa for long-distance sorties against Luzon.

15 Morison, Rising Sun in the Pacific, p. 166.

16 Unless otherwise noted, this section is based on the Philippine Department Plan ORANGE, 1940 Revision. (Short title: HPD WPO-3), AG 326. The author has also had the benefit of conversations with the Philippine Department Commander, General Grunert, with Generals Sutherland and Marshall, and with various division commanders and staff officers who participated in the planning and execution of the plan.

19 Interv, author with Col Diller, 20 May 49. Wainwright mentions also that as Philippine Division commander he worked during May, June, and July 1941 to secure revisions of WPO-3. General Jonathan M. Wainwright, General Wainwright's Story, the Account of Four Years of Humiliating Defeat, Surrender, and Captivity (New York: Doubleday & Company, Inc., 1946), p. 10.

22 Ltr, MacArthur to TAG, 1 Oct 41, sub: Opns Plan R-5, WPD 4178-18. MacArthur repeated the same request, in virtually the same language, in a personal letter to Marshall on 28 October 1951, WPD 4477-2.

23 Memo, Marshall for MacArthur, 18 Oct 41, sub: USAFFE, WPD 4175-18.

24 Brereton, Diaries, p. 19.

25 USAFFE-USFIP Rpt of Opns, p. 15.

26 Ltr, CofS to CG USAFFE, 21 Nov 41, sub: U.S.-British Co-operation in the Far East, WPD 4402-112. The first draft of this letter used the phrase "strong offensive air action" in the place of "strong air operations in the furtherance of the strategic defensive."

27Ibid., incl, extract copy of Changes in Joint Army and Navy Basic War Plan, RAINBOW 5.

42 Colonel Collier was Assistant G-3, USAFFE and later G-3, Luzon Force. He kept these notebooks for his three sons while he was in prison camp. They were loaned to the author, and a photostat copy is on file in OCMH. They will be hereafter referred to as Collier, Notebooks, with the appropriate number.